When the Darkness Comes
by evangeliacollins
Summary: When Percy Jackson witnesses an event that tears him apart from the only life he has ever known, he runs away and is taken in by the Shadowhunters of the Brooklyn Institute. An uprising power that threatens to destroy the Nephilim and Olympus alike forces him to return, but this time as a ruthless demon-hunter. PJO/TMI Crossover, of a sort- full story explained in A/N of Chapter 1.


Percy Jackson was finally happy. He, along with the help of Annabeth and the rest of the Chosen Seven, had defeated Gaea while simultaneously closing the Doors of Death and surviving Tartarus. They, of course, had not escaped unscathed, and he was closer with Annabeth than ever, sharing the burden and pain of their times in Tartarus.

The Romans and Greek had finally made peace and combined forces to stand against the army of monsters that marched their way and had triumphed. There were too many people lost in the war, too much blood spilled. But Annabeth was beside him, as were his friends. His world was at peace, for once in his life. But obviously, being a demigod, it could never last too long.

Percy's world was shattered at the arrival of his new half-brother, Colton Hunter.

Arrogant, manipulative, and conceited, he shredded both his brother's world and heart to bits.

Turning those he called friends against him. Stealing away the person that mattered most to him with false promises and charm.

Percy watched and suffered silently as his life was slowly destroyed. Gone.

It all started one sunny July afternoon, just twenty-two days shy of Percy's birthday.

* * *

_2:37 P.M., July 27th, 2013_

_Camp Half-Blood, Long Island, New York_

_The Beach_

The conch horn rang through the bustling, lively camp, cutting through all conversations.

"New camper!" Travis Stoll yelled. "C'mon! New camper!"

Percy Jackson smiled and sprinted down Half-Blood Hill with his girlfriend, Annabeth Chase laughing with him at his heels.

They stopped at the camp border as a brown-haired boy limped into camp, accompanied by a curly-haired satyr.

"Grover!" Percy called as he ran down to meet the duo.

"Percy," Grover called weakly. "This is Colton. Colton Hunter. I don't know who his father is, but he's powerful."

Percy nodded and tried for a smile. "Hey, Colton. I'm Percy, a son of Poseidon. Welcome to camp. It's the only place for people like us. We'll train you to become a hero, teach you how to stay alive. You're going to be all right now. We're all special like you."

He was expecting a sign of relief or gratitude, at least a kindly smile or a "thank you."

Instead, Percy received a cold glare in response to his friendly welcome. Percy blinked, stunned. If he had looked closer, he would have noticed the smirk that appeared on Colton's grimy face, the malicious glint in his muddy green eyes. He didn't.

Percy turned back to the other campers to mask his confusion. "Come on! Help him inside!"

Colton glared at him again. "I can walk by myself, you know," he spat.

Percy's brow furrowed and he raised his hands in a gesture of surrender. "Okay, dude. Just trying to help."

That was the first sign that things were definitely not going the right way between him and the new camper.

Things took a turn for the worse when the campers had huddled around the campfire. Someone let out a startled cry, piercing through all the joyous shouting and laughter.

"Look!" Someone cried, pointing their finger in the direction of the disturbance. "Look!"

Heads turned. Shouts arose. Gasps echoed throughout the hall.

There, floating above Colton's head, was a glowing green three-tipped trident. The mark of Poseidon.

Percy felt his breath catch in his throat. No, no, no, no, this could not be happening.

"Poseidon," Chiron announced. "Earthshaker, stormbringer, father of horses. All hail, Colton Hunter, son of the sea god."

* * *

Days passed. Already things were not going smoothly between Percy and his new half-brother, Colton.

He had decided that he was, naturally, the better son of Poseidon and the hero of the camp. All day, Percy could see him strutting around the camp grounds like he owned the place, smirking arrogantly as girls fawned over him and guys watched him in awe.

Honestly, he had no idea why girls squealed and sighed as Colton passed by. His features were plain and much less pronounced than Percy's, with lank brown hair and dull, dark green eyes compared to his brother's windswept black hair, defined features, and bright sea green orbs. Percy was several inches taller than Colton, not to mention the obvious difference in their bodies. Instead of Percy's muscular, lean physique, Colton was short and slight, almost scrawny.

Grover had become completely obsessed with Colton, losing all social connection with Percy and not even bothering to IM him. Much to Percy's shock, he found that their empathy link had been severed.

Jason, who had resumed his rightful position as Praetor, also seemed to think that Colton was pretty cool, making no effort to stay in touch with Percy. Piper had turned indifferent towards him, acting as if they were only distant relatives rather assuming the close relationship the two had created in the war. He also hadn't seen Leo much the last few weeks, but according to Annabeth he had been following Colton around like a puppy, cracking lame jokes whenever he had the chance.

Pathetic.

Percy was amazed at how quickly Hazel and Frank turned against him. When before, they had both loved and looked up to him like a big brother, now they completely either ignored him or looked away uncomfortably when he approached them. Like Grover, Frank proceeded to give his undivided attention and worship to Colton, as did Hazel.

Even Chiron had immediately dropped his comforting, fatherly facade and focused entirely on training Colton. Percy couldn't help but watch and remember that proud gleam in his eyes that would light whenever that kind brown gaze fell on him. But not anymore. He wasn't his favorite anymore. To Chiron, Percy was no longer the hero, but the fragment of a memory.

The other campers were no better. They shot him cold glares and whispered his name in disgust as if he was a disgrace to the demigods, and not the courageous hero that they had once treated him like. The only things that kept Percy anchored to his sanity were his cousins, Nico and Thalia- and, of course- Annabeth. Always there to soothe him, to make him laugh, to make him feel like he was worth a million drachmas.

Until that one night. When his world fell apart. When his heart was ripped to shreds.

That night when Perseus Jackson died, and a merciless Shadowhunter was born in his place.

* * *

Percy Jackson stared blankly down at the thin chain entwined in his palm. On it hung a delicate silver ring. The gleaming metal was designed so the two ends twined around the band, connecting at the ends with a single diamond that sparkled alternating sea green and silver when it caught the sunlight.

No, he was not proposing, but simply wanted Annabeth to keep it as a sign of his gratitude, a symbol of their love for each other. A promise ring, of a sort.

But there was one problem.

Perseus Jackson, two-time Hero of Olympus, was afraid. Afraid of being rejected, afraid that he was taking things too quickly.

But- how many times had she gazed up at him with those beautiful, stormy grey eyes and said, I love you? How many times had she pulled him into a sweet kiss with her melodic laugh and a fond, chiding "Seaweed Brain" every time he did something stupid?

The thought gave him confidence. It's not like I'm proposing. Just a promise that I'll always love her. Come on, Percy. You can do this.

With a determined set of his jaw, Percy strode out of his cabin, pushing all thoughts of rejection behind.

Next time I walk in here, I won't be alone, the son of Poseidon thought, certain that a certain beautiful blonde demigod would be accompanying him through the doorway.

But next time would never come.

* * *

Colton strode forward, struggling to catch up with the blonde's quick pace. "Annabeth!" He panted. "Wait up!"

Despite all the attention Colton had been receiving lately from the other campers and whatnot, Annabeth, Nico, and Thalia had been adamantly refusing to admit that Colton was the obviously much better son of Poseidon. Stubborn idiots. Couldn't they see? Percy wasn't a hero, he was a coward! But today, he was determined to make that change.

"Annabeth!"

Said demigod whirled in a flurry of blonde hair, steely eyes narrowed in annoyance. "What do you want?" She hissed.

"I just needed to talk to you," Colton muttered. "Geez."

Annabeth raised a skeptical eyebrow. "Well, then. Go ahead."

"Alone?" He pleaded.

Annabeth exhaled. "Fine, but it better be quick." She turned on her heels and walked off, resuming her brisk stride. Her lips quirked up a fraction of an inch as she noticed how unfit the boy was. They had only just started walking and he was already out of breath.

"Hurry up!" She barked. Percy would have been well ahead of her, but this...this stupid, arrogant half-brother of his couldn't do anything.

Scowling, the boy hurried his way towards the woods, and stopped once they had arrived in a small clearing.

Annabeth bit her tongue to keep from crying out in protest. This was Percy's and her special place, where they always relaxed and lay down side by side, spilling everything that had been bothering them. It was precious, a field full of peaceful memories and kisses and smiles, and even the thought of Colton tainting those moments made her sick. But now, as he stood there and stared at her arrogantly, like it was his... it took all of Annabeth's willpower not to throttle him right then and there and feed him to the harpies.

Chin up and eyes blazing, she crossed her arms and glowered at him defiantly.

"Well?" Annabeth demanded.

Colton simply seated himself and smiled. "Sit."

Annabeth obeyed, eyeing him warily. "Really, what do you want?" She snapped.

He hesitated. "I was just wondering...would you-" His words were cut short when he saw a familiar silhouette approaching the clearing. Tall and lean, with messy black hair. A person that he knew too well, and loathed with all his heart.

Colton jaw set with sudden determination, and as the other demigod looked up, wrapped his arms around Annabeth's waist like a vice and smashed his lips to hers.

* * *

Percy nervously made his way to the Athena cabin. Too soon, he found himself in front of the familiar wooden door, staring blankly at the owl carved into it. Taking a deep breath, he knocked.

The door was answered almost immediately by Annabeth's half-brother, Malcolm. Whereas he would have usually greeted him with a warm "Hey, Percy!", now he simply stared. "What do you want?"

"Um...is Annabeth there?"

"No."

"Oh, um. Okay. Thanks. Bye."

Malcolm slammed the door in his face before he could say anything else. Embarrassed, Percy shuffled away. Why was everybody treating him like that? Like he was some kind of burden on them, not the two-time hero of Olympus? Sure, he was a modest person, but that definitely did not mean that he didn't appreciate a little respect.

Didn't he at least he deserve some kind of credit? A sign of approval, saying that they were proud of him, that they were grateful for what he had done? Percy shook his head, confused. Maybe a walk in the woods would clear his mind a little before dinner.

He trudged through the heavy green scenery, startling the occasional dryad or nature spirit, who hissed in annoyance every time he passed by. Really? Now the trees hated him too? He understood that the claiming of a new son of Poseidon was exciting, yes. But had Colton done anything for them? Why were they treating him like the hero when Percy had done all the work?

His thoughts drifted back to Luke. He was seventeen now, only two years younger than Luke had been when he first was enslaved to Kronos. Percy got where Luke was coming from now. He was tired of being a pawn of the Olympians. Risking his life and sanity while the gods messed with his memories and made his life as hard as it could possibly get. What did it matter if they were family? The gods had done nothing for him.

Eyes downcast and expression troubled, he headed towards the spot he and Annabeth would always relax in- that one tiny clearing, where the grass was soft and green and the sky always shone clear blue, clouds drifting lazily in and out of their field of vision like cotton candy. Holding hands, they would always lie down side by side, staring up at the sky and telling each other their troubles and doubts. It brought back memories of peaceful afternoons spent together, of gentle smiles and feather-light kisses. Who knew? Maybe Annabeth would be there, and Percy could surprise her with the ring.

He smiled softly as he imagined the scene in his head. He could almost see himself giving her the ring, Annabeth jumping up with delight and throwing her arms around him, and a sweet kiss followed by exchanged 'I-love-you' s and peals of laughter. The son of Poseidon trudged on, his steps considerably lightened by the inexhaustible spark of human hope.

Maybe things could get better. It didn't matter how bad things became. Annabeth would always be with him.

He had never been more wrong in his life.

* * *

**Hello, my lovely readers!**

**So, um. I'm alive. I'm so absolutely sorry for not updating in so long, but the past few months have kind of been a whirlwind. **

**But all excuses aside, let's get into the story- so this is the story briefly mentioned in the A/N of my PJO/HP crossover, "American Exchange." I asked you about starting a new Percy Jackson/The Mortal Instruments crossover fic (as you can tell, I kind of like writing crossovers, heh). I did get several requests to post the first chapter, and after months of delay, here it is! **

**"When the Darkness Comes" is a song by Colbie Caillat made for the City of Bones soundtrack, and after a few listens, I fell in love with the voice and the lyrics in itself. I feel like it portrays the emotion of this story perfectly, and if you haven't already, please give it a listen! It's slightly melancholy and very different from other popular songs these days (which, can I say, I hate?), but I do really love it. **

**The plot line of this story has been hinted already in this chapter, but just for the readers who didn't catch on (guilty as charged, I know I do that big-time), it will be modeled after the generic Percy Jackson Chaos stories where Percy gets betrayed, leaves his past behind, and returns some time later as a badass assassin of Chaos, Gaea, or something of the sort. However, because I do wish to stray a little bit from the predictable course of events, I will be adding my own little twists. **

**For example, instead of turning into a ruthless assassin of Chaos, Percy will be having a little stay with the Shadowhunters of Brooklyn, which ties in the Mortal Instruments series. And, even by just reading the first chapter, Annabeth won't be some kind of Regina George character who just decides to cheat on Percy with Colton, because-**

**1) Ew. The OOCness of that version of Annabeth makes my skin crawl.**

**2) I ship Percabeth to a somewhat unhealthy degree, and I would _never, ever_ even think to split them apart. **

**So, as explained in my "American Exchange" author's note, this story will be under the regular PJO archive and not the PJO/TMI crossover one, because it is a section that very few people look into, and I feel that both my readers and I as an author would benefit from putting this story out to a larger audience. **

**As always, thank you for your support! I'm so sorry for the delay, but I love you all and remember to follow, favorite, and review :)**

**- Lia **

**(Whoops. My username was previously "lolagurrl27". I'm now using my real name, Evangelia Collins, but most people just call me Lia.)**


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